Debugging And Tracing Ultimate Module

Carp::Datum implements the following features:

* Programming by contract: pre-conditions, post-conditions, assertions.
* Flow control tracing: routine entry, arguments, returned values
* Dynamic (i.e. runtime) configuration via mini language to tailor
  debugging and/or tracing at the routine / file / package / type level.
* Ability to statically remove all assertions and flow control tracing
  hooks in modules making use of Carp::Datum.
* Cooperation with Log::Agent for tracing.
